Cobot Safety

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The exciting thing about Cobots in manufacturing is their ability to interact safely with humans while both are working. But what does ‘safely’ mean in this context? Much like Arthur C. Clarke’s fictional law “A Robot may not injure a human being…” it sounds good in theory but is very much up to interpretation. How do we define ‘safe’ in a way that is universally accepted?

The ISO (International Standards Organisation) / TS (Technical Specification) 15066 is a document released in 2016 after six years of research that aims to do just this. It defines design criteria, maximum speeds of movement, and maximum force that can be safely applied to a human through knocks, known as ‘Transient Contact’, or through a pinch, known as ‘Quasi-Static Contact’ as well as 33 pages of other details. It was compiled by committee ISO/TC 299, the committee responsible for Robotics standards, (excluding toys and military applications), but the experts on the committee had the same basic problem when coming up with the specific force and speed limits. What constitutes an injury?

The IFA (roughly translated: Institute For Organisational Health and Safety) in Germany conducted a study in 2014 to find the pain threshold of the average healthy worker. One hundred brave souls volunteered to be strapped into a test jig, where an automatic Algometer (a device used to measure pain thresholds) slowly poked them with a 14 x 14mm rounded steel plunger. When the pressure changed from uncomfortable to painful, they would press a button, and the pressure was recorded. This process was then repeated in 28 other body locations on each subject. When this Machiavellian machine of mild discomfort had finished its work, there were 9000 pain measurement data points to be statistically analyzed and turned into a Pain Threshold Map. It was found that subjects’ pain thresholds varied widely, with gender, as well as occupation, being strong predictors.

The results of this study, as well as a number of other historical studies, informed the decisions of the ISO committee in deciding what an injury is and what defines a robot as safe. As a result, the robotics industry now has strict collaboration standards that allow people to work alongside Cobots with comfort and ease.

 

1 https://www.iso.org/standard/62996.html

2 https://www.iso.org/committee/5915511.html

3 https://www.dguv.de/ifa/index-2.jsp

4 https://www.dguv.de/ifa/fachinfos/kollaborierende-roboter/schmerzschwellenkataster/index-2.jsp

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